Artery Dissection and Arterial Thrombus Aging
The Role of Noninvasive Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) has the potential to study atherosclerotic lesions noninvasively, and it is considered a valid method for the detection of deep venous thrombosis. An organized/old thrombus is considered one of the most thrombogenic substrates. Therefore, noninvasive detection and differentiation between recent and old arterial thrombi is an important goal for diagnostic imaging. Aortic dissection was detected in a rabbit model of atherosclerosis after balloon injury using MR angiography and black-blood cross-sectional images (Figure 1⇓). A low-intensity signal area compatible with slow flow and/or fresh thrombus was seen in the false lumen. Sequential MR indicated a progressive decrease of the residual blood flow in the false lumen, and the MR signal intensity of the surrounding thrombus increased (Figure 2⇓). The correlation of the histopathological analysis of the corresponding arterial segments with the MR signal obtained using T1-weighted black-blood sequencing allowed us to differentiate the matrix (hypointense MR signal) from various stages of hemoglobin-degrading products (Figures 3E⇓ and 3F⇓). Methemoglobin-rich areas corresponded to the hyperintense MR signal, and hemosiderin-rich areas corresponded to the isointense MR signal. This case provides evidence of the potential of noninvasive MR for the detection of fresh thrombus. In addition, by using an adequate MRI sequence (ie, T1-weighted), MR may further characterize the age of the thrombus.
Detection of thrombotic material in the arterial circulation and the exact definition of its age remain a crucial clinical challenge for noninvasive diagnosis. Noninvasive MRI is a very promising tool and should be validated for the human circulation.
- Copyright © 2001 by American Heart Association